Heat pump system for vehicle

ABSTRACT

A heat pump system may include a cooling assembly disposed on a vehicle to circulate electric devices with coolant through a cooling line, wherein the cooling assembly includes a radiator disposed at a front side of the vehicle, uses a water pump to circulate coolant through the cooling line, and cools the supplied coolant through heat exchange with outside air, and a cooling fan that blows wind through the radiator, an air conditioning assembly connected to a refrigerant line connected to the cooling assembly to control heating and cooling, and a heat exchanger connected to the cooling line such that the coolant is circulated therein, selectively uses the waste heat generated from the electric devices according to modes to vary the temperature of the coolant, and is connected to the refrigerant line of the air conditioning assembly such that an inflow refrigerant exchanges heat with the coolant.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2011-0059768 filed in the Korean Intellectual Property Office on Jun. 20, 2011, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat pump system and a control method thereof. More particularly, the present invention relates to a heat pump system that uses waste heat that is generated from electric devices, improves heating and dehumidifying performance, prevents front accumulation on an outside condenser at a low temperature, and simultaneously increases a travel distance, and a control method thereof.

2. Description of Related Art

Generally, an air conditioning system for a vehicle includes an air conditioning module warming or cooling a cabin of the vehicle.

Such an air conditioning module circulates a heat-exchanging medium through a condenser, a receiver drier, an expansion valve, and an evaporator by operation of a compressor. After that, the heat-exchanging medium flows back to the compressor. At this process, the air conditioning module warms up the cabin of the vehicle through heat exchange at the evaporator or cools the cabin of the vehicle through heat exchange with a coolant at a heater.

Meanwhile, energy efficiency and environmental pollution are of increasing concern, and environmentally friendly vehicles substituting for vehicles having an internal combustion engine have been researched. Such environmentally-friendly vehicles include electric vehicles using a fuel cell or electricity as a power source, and hybrid vehicles driven by an engine and an electric battery.

An electric vehicle among an environmentally friendly vehicle uses an electric heater, because the electric vehicle does not have a combustion engine as a heat source.

But, the electric heater excessively consumes electric power to reduce a travel distance of the electric vehicle. A heater pump system having an improved heating efficiency is introduced instead of the electric heater so as to resolve this problem.

According to the heat pump system, a high temperature/pressure gaseous refrigerant compressed at a compressor is condensed at a condenser and is then supplied to an evaporator passing through a receiver drier and an expansion valve in a cooling mode in the summer. The gaseous refrigerant is evaporated at the evaporator and lowers temperature and humidity of the cabin. However, the heat pump system has characteristics that the high temperature/pressure gaseous refrigerant is used as a heater medium in a warming mode in the winter.

That is, the high temperature/pressure gaseous refrigerant is supplied not to an exterior condenser but to an interior condenser through a valve and is heat-exchanged with air in the warming mode in the electric vehicle. The heat-exchanged air passes through a positive temperature coefficient (PTC) heater. After that, the air flows into the cabin of the vehicle and raises the cabin temperature of the vehicle.

The high temperature/pressure gaseous refrigerant flowing into the interior condenser is condensed through heat exchange with the air and flows out in a state of liquid refrigerant.

However, a conventional heat pump system as described above is an air-cooled type in which the refrigerant is cooled by outside air.

Also, the refrigerant that is cooled by outside air of a very low temperature or a low temperature in winter is cooled by an interior condenser to be exhausted in a very low temperature condition to an outside condenser, and therefore ice is formed on a surface of the outside condenser and heat exchange efficiency of the heat exchange media and heating performance and efficiency are deteriorated, and in a case that the cooling mode is transformed to the heating mode, the condensate that stays on the evaporator increases humidity such that moisture is formed on the interior of the glass of the vehicle.

To solve such problems, the compressor stops operating and warming is performed only by the PTC heater in a defrosting mode where a surface of the exterior condenser is defrosted. Therefore, heating performance may be seriously deteriorated, the heating load may be increased due to the increase of power consumption, and the mileage may be decreased when driving while warming.

In addition, since heat for converting the liquid refrigerant into a gaseous refrigerant is insufficient when the liquid refrigerant flows into the interior condenser, compressing efficiency may be deteriorated, heating performance may be seriously deteriorated when the air temperature is low, the system may be unstable, and durability of the compressor may be deteriorated when the liquid refrigerant flows into the compressor

In addition, noise and vibration may occur due to a frequent open/close operation of a 2-way valve in a dehumidification mode where moisture is removed from the cabin of the vehicle.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a heat pump system for a vehicle having advantages of using a waste heat source in electric devices to heat coolant and exchanging the heat between the coolant and refrigerant to improve heating performance and dehumidification efficiency, and to prevent frost accumulation on the outside condenser in a low temperature, and a control method thereof.

Also, various aspects of the present invention are directed to providing a heat pump system for a vehicle having advantages of reducing a heating load in a heating mode of a vehicle and increasing overall travel distance of a vehicle with same power source, and a control method thereof.

In an aspect of the present invention, a heat pump system may include a cooling assembly that is disposed on a vehicle to circulate electric devices with coolant through a cooling line, wherein the cooling assembly may include a radiator that is disposed at a front side of the vehicle, uses a water pump to circulate coolant through the cooling line, and cools the supplied coolant through heat exchange with outside air, and a cooling fan that blows wind through the radiator, an air conditioning assembly that is connected to a refrigerant line connected to the cooling assembly to control heating and cooling, and a heat exchanger that is connected to the cooling line such that the coolant is circulated therein, selectively uses the waste heat that is generated from the electric devices according to modes to vary the temperature of the coolant, and is connected to the refrigerant line of the air conditioning assembly such that an inflow refrigerant exchanges heat with the coolant.

The air conditioning assembly may include an HVAC (Heating, Ventilation, and Air Conditioning) module that is provided with an evaporator and an opening/closing door therein, wherein the opening/closing door is selectively closed such that outside air passing the evaporator is supplied to an inner condenser and a PTC heater according to heating, cooling, and dehumidifying modes, a compressor that is connected to the evaporator through a refrigerant line and compresses gaseous refrigerant, an accumulator that is disposed on the refrigerant line between the compressor and the evaporator and that supplies the compressor with gaseous refrigerant, an outside condenser that is disposed in an engine compartment of the vehicle, is connected to the refrigerant line, and condenses refrigerant, a first valve that selectively supplies the inner condenser or the outside condenser with the refrigerant that is exhausted from the compressor according to a mode of the vehicle, a first expansion valve that receives the refrigerant passing the inner condenser to expands the refrigerant, a second valve that selectively supplies the outside condenser or the heat exchanger with the expanded refrigerant received from the first expansion valve, a third valve that selectively supplies the evaporator or the accumulator with the refrigerant passing the outside condenser or the heat exchanger, and a second expansion valve that connects the evaporator and the third valve and expands the refrigerant that is supplied through the third valve.

A pressure sensor is disposed on the refrigerant line connecting the compressor with the first valve.

The first, second, and third valves are a type of 3-way valve.

The cooling assembly and the air conditioning assembly are respectively connected to a controller to be operated by a control signal of the controller.

In another aspect of the present invention, a heat pump system control method for a vehicle that is applied to a heat pump system that may include a cooling assembly that is connected to a controller and may include a radiator, a water pump, and electric devices, each of which is connected through a cooling line, an air conditioning assembly connected by a refrigerant line and including an HVAC (Heating, Ventilation, and Air Conditioning) module that may have a plurality of valves, an expansion valve, a compressor, an accumulator, an evaporator, an outside condenser, an inner condenser, a PTC heater, and an opening/closing door, and a heat exchanger that is connected to the cooling line and the refrigerant line, and is used to operate a heating mode, a cooling mode, and a humidifying mode according to a selection of a user, wherein during the heating mode, raising by the cooling assembly, the temperature of coolant that is supplied to the heat exchanger through waste heat that is generated from the electric devices and raising the temperature of refrigerant through heat exchange with the refrigerant that is supplied to the heat exchanger through the refrigerant line, passing by the air conditioning assembly the refrigerant that is heated by the heat exchanger through the accumulator and the compressor via the refrigerant line by opening a third valve to be supplied to an inner condenser of the HAVC module by an operation of a first valve, supplying the refrigerant passing the inner condenser to the heat exchanger by an operation of a second valve in an expanded condition through a first expansion valve, and opening the opening/closing door such that outside air passing the evaporator of the HAVC module passes the inner condenser, and inflow outside air passes the inner condenser to heat an interior room of the vehicle in conjunction with the operation of the operation of a PTC heater.

In the cooling mode, operating the water pump by the cooling assembly to supply coolant to the heat exchanger and to cool the electric devices in a condition that the radiator cools inflow coolant by an operation of a cooling fan, and cools refrigerant through heat exchange with low temperature coolant according to a predetermined condition, operating the third valve by the air conditioning assembly to supply the evaporator with expanded refrigerant such that the low temperature refrigerant that is cooled passing the outside condenser is supplied to the second expansion valve that is connected to the evaporator of the HAVC module, wherein the refrigerant that is evaporated through heat exchange with outside air in the evaporator passes the accumulator and the compressor to be compressed, operating the first valve to open the refrigerant line that is connected to the outside condenser such that a compressed refrigerant is supplied to the outside condenser, and closing the opening/closing door such that the outside air passes the evaporator to be cooled by the refrigerant supplied to the evaporator and is directly supplied to an interior room of a vehicle and that the cooled outside air is not supplied to the inner condenser.

In the dehumidification mode, cooling the coolant that is supplied to the radiator by the operation of the cooling fan of the cooling assembly, cooling the electric devices through the operation of the water pump, supplying the coolant to the heat exchanger, and cooling the refrigerant by exchanging heat with the coolant supplied to the heat exchanger, opening the third valve by the air conditioning assembly such that the coolant that is cooled while passing the heat exchanger is supplied to the second expansion valve that is connected to the evaporator of the HAVC, so as to supply the expanded refrigerant to the evaporator, wherein the refrigerant that is evaporated through heat exchange with outside air in the evaporator passes the accumulator and the compressor to be compressed, operating the first valve to open the refrigerant line that is connected to the inside condenser such that the compressed refrigerant is supplied to the inside condenser, operating the second valve to supply the refrigerant passing the inner condenser to the heat exchanger in an expanded condition through the first expansion valve, opening the opening/closing door such that outside air passing the evaporator of the HAVC module passes the inner condenser, and inflow outside air passes the inner condenser and the PTC heater to dehumidify an interior room of the vehicle.

In the dehumidification mode, the controller controls an opening rate of the first and second expansion valves to control an expansion rate of the refrigerant.

In the heating mode, cooling mode, and dehumidification mode, the controller controls operating power of the cooling fan and flowing rate of the water pump according to the temperature of the waste heat that is generated from the electric devices and the temperature of the coolant and the refrigerant.

The heat pump system control method may further include a four valve that is configured to make coolant to bypass the radiator according to a heating mode and a dehumification mode.

In the heat pump system for a vehicle and the control method according to an exemplary embodiment of the present invention, a heat exchanger using coolant as a heat exchange assembly is applied and a waste heat source from the electric devices is used to exchange heat with the refrigerant to improve heating performance, efficiency, and dehumidification performance and to prevent the frost accumulation on the outside condenser in chilly weather.

Also, in the heating mode, the overall system is simultaneously operated with an operation of the PTC heater during an idle condition and driving condition in very chilly weather to prevent the increment of the power usage such that the heating load is reduced to increase travel distance of the vehicle with the same power.

Further, in the cooling mode of the vehicle, the system maintains air conditioner condition of air cooled type through an outside condenser to improve cooling performance, and the first, second, and third valves are 3-way valves to reduce frequent opening/closing operations such that the noise and vibration can be reduced.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a heat pump system for a vehicle according to an exemplary embodiment of the present invention.

FIG. 2 shows an operational state of a heat pump system for a vehicle according to an exemplary embodiment of the present invention.

FIG. 3 shows a cooling mode state of a heat pump system for a vehicle according to an exemplary embodiment of the present invention.

FIG. 4 shows a dehumidification mode state of a heat pump system for a vehicle according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a heat pump system for a vehicle according to an exemplary embodiment of the present invention.

Referring to the drawings, the heat pump system 100 for a vehicle and the control method thereof according to an exemplary embodiment of the present invention use waste heat that is generated from electric devices, improves heating and dehumidifying performance, prevents the front accumulation on an outside condenser at a low temperature, and simultaneously increases a travel distance.

Also, a heating load that can be generated in a heating mode of a vehicle is reduced to increase overall travel distance of a vehicle with the same fuel amount.

For this purpose, the heat pump system 100 for the vehicle according to an exemplary embodiment of the present invention, as shown in FIG. 1, includes a cooling assembly 110 that is disposed in a vehicle to supply and circulate coolant to electronic devices 111 and an engine in a hybrid vehicle through a cooling line (hereinafter “C.L”), and an air conditioning assembly 150 that is connected to a refrigerant line (hereinafter “R.L”) to control interior cabin heating and cooling of the vehicle.

In the present exemplary embodiment, the cooling assembly 110 includes a radiator 115 that is disposed at the front of the vehicle to circulate coolant along the cooling line (C.L.) through a water pump 113 and cools the coolant through heat exchange with outside air, and a cooling fan 117 that is disposed at the rear of the radiator 115.

And, the heat pump system 100 includes a heat exchanger 130 that is disposed between the electric devices 111 and the radiator 115 to be respectively connected to the cooling line (C.L) and the refrigerant line (R.L).

The heat exchanger 130 is connected to the cooling line (C.L) to circulate coolant, and selectively uses the waste heat source that is generated from the electric devices to vary the temperature of the coolant depending on a heating mode, a cooling mode, and a dehumidification mode such that the refrigerant that is supplied through the refrigerant line (R.L) exchanges heat with the coolant.

That is, the heat exchanger 130 can be a water cooling type that uses a coolant to exchange heat with the refrigerant.

The heat exchanger 130 includes a temperature sensor that is disposed therein, and the temperature sensor can detect the temperature of the coolant and the refrigerant.

In the present exemplary embodiment, the air conditioning assembly 150 includes an HVAC module (heating, ventilation, and air conditioning, 151), a compressor 161, an accumulator 163, an outside condenser 164, first, second, and third valves 165, 167, and 169, and first and second expansion valves 171 and 173, and they are explained as follows.

First, the HVAC module 151 includes an evaporator 157 cooling air and an inner condenser 153 heating the air passing the evaporator 157, and an opening/closing door 159 is disposed therein, wherein the opening/closing door 159 is controlled such that the outside air passing the evaporator 157 is selectively supplied to the inner condenser 153 and a PTC heater 155 depending on the cooling, the heating, and the dehumidification modes.

That is, the opening/closing door 159 is opened to make the outside air pass the evaporator 157 be supplied to the inner condenser 153 and the PTC heater 155 in the heating mode of the vehicle, and the door 159 is closed to make the outside air passing the evaporator 157 be supplied to the interior room of the vehicle.

In the present exemplary embodiment, the compressor 161 is connected to the evaporator 157 through the refrigerant line (R.L) to compress the gaseous refrigerant.

And, the accumulator 163 is disposed on the refrigerant line (R.L) between the compressor 161 and the evaporator 157, stores the liquid refrigerant therein, and supplies gaseous refrigerant to the compressor 161 to improve efficiency and durability of the compressor 161.

The outside condenser 164 is disposed at a front side of the radiator of the vehicle to be connected to the refrigerant line (R.L), and receives the refrigerant exhausted from the compressor 161 to condense the refrigerant.

The first valve 165 selectively supplies the inner condenser 153 or the outside condenser with the refrigerant that is exhausted from the compressor 161 depending on the mode of the vehicle in the present exemplary embodiment.

The first expansion valve 171 receives the refrigerant passing the inner condenser 153 through the refrigerant line (R.L) and expands it.

Here, a pressure sensor 175 is disposed on the refrigerant line (R.L) between the compressor 161 and the first valve 165, and the pressure sensor 175 detects the pressure of the compressed refrigerant that is exhausted from the compressor 161.

The second valve 167 selectively supplies the outside condenser 164 and the heat exchanger 130 with the refrigerant that is expanded by the first expansion valve 171.

The third valve 169 selectively supplies the evaporator 157 or the accumulator 163 with the refrigerant passing the heat exchanger 130 or the outside condenser 164.

And, the second expansion valve 173 is disposed between the evaporator 157 and the third valve 169 to expand the inflow refrigerant and supplies the evaporator 157 with the expanded refrigerant through the third valve 169.

Here, the first valve 165 is used to direct the refrigerant to the inner condenser 153 or the heat exchanger 130, the second valve 167 is used to direct the refrigerant to the heat exchanger 130 or the outside condenser 164, and the third valve 169 is used to direct the refrigerant to the accumulator 163 or the second expansion valve 173, wherein the valves 165, 167, and 169 can be 3-way valves that selectively connect the refrigerant line (R.L).

The cooling assembly 110 and the air conditioning assembly 150 that have the above configuration are respectively connected to a controller 180 to be operated by the control signal of the controller 180.

That is, the controller 180 controls the cooling fan 117 and the water pump 113 of the cooling assembly 110 according to the heating mode, the cooling mode, and the dehumidification mode, and the signal that is outputted from the temperature sensor of the heat exchanger 130.

Also, the controller 180 controls the opening/closing door 159 of the HVAC module 151 in the air conditioning assembly 150 depending on the mode of the vehicle, and simultaneously controls the first, second, and third valves 165, 167, and 169, and controls the first and second expansion valves 171 and 173 to control the expansion amount of the refrigerant.

Hereinafter, referring to FIG. 2 to FIG. 4, the operation of a heater pump system for a vehicle and the control method thereof will be described according to an exemplary embodiment of the present invention.

FIG. 2 to FIG. 4 show operational states of a heating mode, a cooling mode, and a dehumidification mode of a heat pump system for a vehicle according to an exemplary embodiment of the present invention.

Here, the heating mode, the cooling mode, and the dehumidification mode of the heat pump system 100 can be operated by a selection of a user or automatic control.

First, referring to FIG. 2, the heating mode of the heat pump system 100 will be explained.

Referring to FIG. 2, the cooling assembly 110 heats the coolant by using the waste heat source of the electric devices 111 and supplies the heated coolant to the heat exchanger 130 connected to the cooling line (C.L) in the heating mode.

In this case, the cooling fan 117 can be stopped or operated in a slow speed to delay or to prevent the cooling of the coolant that is supplied to the radiator 117.

In this condition, the heat exchanger 130 raises the temperature of the coolant through the heat exchange with the coolant that is supplied through the refrigerant line (R.L).

Here, the controller 180 detects the temperature of the coolant and the refrigerant through the temperature sensor that is disposed in the heat exchanger 130, and controls the operation level of the water pump 113 and the cooling fan 117 depending on the temperature of the waste heat from the electric devices 111, the temperature of the coolant, and the temperature of the refrigerant.

And, the air conditioning assembly 150 controls the third valve 169 to supply the accumulator 163 and the compressor 161 with the coolant that is heated by the coolant in the heat exchanger through the refrigerant line (R.L).

Accordingly, refrigerant passes the compressor 161 to be compressed to a gaseous condition having a high temperature and high pressure to be supplied to the inner condenser 153 by the opening of the first valve 165 on the refrigerant line (R.L) that is connected to the inner condenser 153.

Here, the pressure sensor 175 that is disposed on the refrigerant line (R.L) between the compressor 161 and the first valve 165 measures the pressure of the coolant that is exhausted from the compressor 161 to transfer the measured value to the controller 180.

The controller 180 detects the pressure of the coolant depending on the value measured by the pressure sensor 175 to control the opening rate of the first valve 165 according to the vehicle condition demanded.

The coolant passing the inner condenser 153 is expanded by the first expansion valve 171 to flow along the refrigerant line (R.L), is supplied to the heat exchanger 130 through the operation of the second valve 167, and circulates in the refrigerant line (R.L) through the operation as described above.

That is, if the high temperature and high pressure gaseous refrigerant is supplied to the inner condenser 153 in the heating mode, the controller 180 opens the opening/closing door 159 such that outside air passing the evaporator 157 of the HAVC module 151 is supplied to the inner condenser 153.

Thus, when the inflow outside air passes the evaporator that the refrigerant is not supplied therein, the outside air is not cooled by the evaporator 157 and is supplied to the inner condenser 153 to be heated thereby, and the heated outside air is supplied to the interior room of the vehicle with a selective operation of the PTC heater 155.

The operation of the cooling mode of the heat pump system 100 and the control method thereof will be explained in the present exemplary embodiment with reference to FIG. 3.

Firstly, as shown in FIG. 3, the cooling assembly 110 operates the cooling fan 117 through the controller 180 to cool the coolant circulating in the radiator 115 in the cooling mode.

In this process, the cooling fan 117 is operated at a maximum speed to effectively cool the coolant circulating in the radiator 115.

In this condition, the cooled coolant is circulated by the water pump 115 through the cooling line (C.L) to cool the electric devices 111.

Here, the controller 180 detects the coolant temperature through the temperature sensor disposed in the heat exchanger 130, controls the flow rate of the water pump 113, or controls the flow rate of the cooling fan 117 according to the temperature of the waste heat source of the electric devices 111 and the temperature of the coolant.

And, the air conditioning assembly 150 controls the first valve 165 to open the refrigerant line (R.L) that is connected to the outside condenser 164 such that the refrigerant that is exhausted from the compressor 161 is supplied to the outside condenser 164 to be condensed.

In this process, the outside condenser 164 is disposed at a front side of the radiator 115 that is disposed at a front side of the vehicle, and therefore the coolant circulating in the condenser 164 is cooled and condensed by the wind flowing into the front side of a vehicle and the wind that is formed by the cooling fan 117.

Thereafter, the controller 180 controls the third valve 169 to open the refrigerant line (R.L) such that the refrigerant passing the outside condenser 164 is supplied to the second expansion valve 173 that is connected to the evaporator of the HAVC module 151.

The low temperature coolant that flows into the second expansion valve 175 is expanded to be supplied to the evaporator 157 through the refrigerant line (R.L).

Next, the refrigerant is evaporated in the evaporator 157 through the heat exchange with the outside air and passes the accumulator 163 and the compressor 161 along the refrigerant line (R.L) to be compressed.

The first valve 165 is opened to open the refrigerant line (R.L) that is connected to the outside condenser 164 such that the coolant that is compressed through the above process flows into the outside condenser 164 and circulates in the refrigerant line (R.L) while repeating the operations as described above.

Here, the outside air flowing into the HVAC module 151 passes the evaporator 157 to be cooled by the low temperature refrigerant that flows into the evaporator 157.

The opening/closing door 159 closes the passage connected to the inner condenser 153 and the cooled outside air does not pass the inner condenser 153 and the PTC heater 155 such that the cooled outside air is directly supplied to the interior room of the vehicle.

The dehumidification mode of the heat pump system 100 will be described with reference to FIG. 4.

Firstly, as shown in FIG. 4, the cooling assembly 110 controls the cooling fan 117 to be operated by the controller 180 and to cool the coolant flowing into the radiator 115 in the dehumidification mode.

In this condition, the cooled coolant circulates in the cooling line (C.L) through the operation of the water pump 115 to cool the electric devices 111 and is supplied to the heat exchanger 130, and the coolant flowing into the heat exchanger 130 cools the refrigerant through the heat exchange.

Here, the controller 180 detects the coolant temperature through the temperature sensor disposed in the heat exchanger 130 and controls the flow rate of the water pump 113 or controls the flow rate of the cooling fan 117 according to the temperature of the waste heat source of the electric devices 111, the coolant temperature, and the coolant pressure.

The air conditioning assembly 150 operates the third valve 169 to open the refrigerant line (R.L) such that the low temperature refrigerant that is cooled by the low temperature coolant of the heat exchanger 130 is supplied to the second expansion valve 173 that is connected to the evaporator 157 of the HAVC module 151.

Thus, the low temperature refrigerant flowing into the second expansion valve 173 is expanded to be supplied to the evaporator 157 through the refrigerant line (R.L).

Thereafter, the refrigerant is evaporated through the heat exchange with outside air in the evaporator 157, and passes the accumulator 163 and the compressor 161 through the refrigerant line (R.L) to be compressed to a high temperature and high pressure gaseous refrigerant.

The refrigerant line (R.L) that is connected to the inner condenser 153 is opened by the first valve 165 such that the compressed gaseous refrigerant is supplied to the inner condenser 153.

Here, the pressure sensor 175 that is disposed on the refrigerant line (R.L) between the compressor 161 and the first valve 165 detects the pressure of the refrigerant that is exhausted from the compressor 161 to output the value to the controller 180.

The controller 180 uses the value measured by the pressure sensor 175 to detect the refrigerant pressure and controls the opening rate of the first valve 165 according to the demanded condition of the vehicle.

The refrigerant passing the inner condenser 153 is expanded by the first expansion valve 171 to be supplied to the heat exchanger 130 by the opening of the second valve 167 through the refrigerant line (R.L) that is connected to the heat exchanger 130, and circulates in the refrigerant line (R.L) while repeating the above processes.

In this case, the controller 180 controls the opening rate of the first and second expansion valves 171 and 173 to control the expansion rate of the refrigerant.

Here, the outside air flowing in the HVAC module 151 passes the evaporator 157 to be cooled by the low temperature refrigerant flowing into the evaporator 157.

In this case, the opening/closing door 159 opens the part that is connected to the inner condenser 153 such that the cooled outside air passes the inner condenser 153, the inflow outside air passes the evaporator 157 to be dehumidified to be heated through the inner condenser 153, and the dehumidified outside air flows into the vehicle to dehumidify the interior room thereof.

Meanwhile, in a heat pump system for a vehicle and the control method thereof according to an exemplary embodiment of the present invention, it is described that the PTC heater 155 is operated with the outside air in the heating mode as an exemplary embodiment, but it is not limited thereto, and the PTC heater 155 can be selectively operated according to a heating temperature set by a user.

Accordingly, in a heat pump system 100 for a vehicle and a control method according to an exemplary embodiment of the present invention, a heat exchanger using coolant as a heat exchange assembly is applied and a waste heat source from the electric devices 111 is used to exchange heat with the refrigerant to improve heating performance, efficiency, and dehumidification performance and to prevent the frost accumulation on the outside condenser in chilly weather.

Also, in the heating mode, the overall system is simultaneously operated with an operation of the PTC heater 155 during an idle condition and a driving condition in very chilly weather to prevent the increment of the power usage such that the heating load is reduced to increase travel distance of the vehicle with the same power.

Further, in the cooling mode of the vehicle, the coolant is cooled by the low temperature refrigerant to be able to improve the cooling performance, and the first, second, and third valves (165, 167, and 169) are 3-way valves to reduce frequent opening/closing operations such that the noise and vibration can be reduced.

Also, coolant is used as a heat exchange assembly in the heat exchanger 130 to simplify the structure of the respective constituent elements, and simultaneously one radiator 115 is used to cool the electric devices such that the overall system is reduced and efficiency of the radiator 115 is improved.

Referring to FIG. 4, the heat pump system control method includes a four valve 190 that is configured to make coolant to bypass the radiator according to a heating mode and a dehumification mode.

Meanwhile, in a heat pump system for a vehicle and the control method according to an exemplary embodiment of the present invention, the first, second, and third valves are provided as an exemplary embodiment, but it is not limited thereto, and a separate 2-way valve can be applied on the cooling line and the refrigerant line to control flow rate or to bypass the operating fluid, coolant, or refrigerant.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. A heat pump system, comprising: a cooling assembly that is disposed on a vehicle to circulate electric devices with coolant through a cooling line, wherein the cooling assembly includes a radiator that is disposed at a front side of the vehicle, uses a water pump to circulate coolant through the cooling line, and cools the supplied coolant through heat exchange with outside air, and a cooling fan that blows wind through the radiator; an air conditioning assembly that is connected to a refrigerant line connected to the cooling assembly to control heating and cooling; and a heat exchanger that is connected to the cooling line such that the coolant is circulated therein, selectively uses the waste heat that is generated from the electric devices according to modes to vary the temperature of the coolant, and is connected to the refrigerant line of the air conditioning assembly such that an inflow refrigerant exchanges heat with the coolant.
 2. The heat pump system of claim 1, wherein the air conditioning assembly includes: an HVAC (Heating, Ventilation, and Air Conditioning) module that is provided with an evaporator and an opening/closing door therein, wherein the opening/closing door is selectively closed such that outside air passing the evaporator is supplied to an inner condenser and a PTC heater according to heating, cooling, and dehumidifying modes; a compressor that is connected to the evaporator through a refrigerant line and compresses gaseous refrigerant; an accumulator that is disposed on the refrigerant line between the compressor and the evaporator and that supplies the compressor with gaseous refrigerant; an outside condenser that is disposed in an engine compartment of the vehicle, is connected to the refrigerant line, and condenses refrigerant; a first valve that selectively supplies the inner condenser or the outside condenser with the refrigerant that is exhausted from the compressor according to a mode of the vehicle; a first expansion valve that receives the refrigerant passing the inner condenser to expands the refrigerant; a second valve that selectively supplies the outside condenser or the heat exchanger with the expanded refrigerant received from the first expansion valve; a third valve that selectively supplies the evaporator or the accumulator with the refrigerant passing the outside condenser or the heat exchanger; and a second expansion valve that connects the evaporator and the third valve and expands the refrigerant that is supplied through the third valve.
 3. The heat pump system of claim 2, wherein a pressure sensor is disposed on the refrigerant line connecting the compressor with the first valve.
 4. The heat pump system of claim 2, wherein the first, second, and third valves are a type of 3-way valve.
 5. The heat pump system of claim 1, wherein the cooling assembly and the air conditioning assembly are respectively connected to a controller to be operated by a control signal of the controller.
 6. A heat pump system control method for a vehicle that is applied to a heat pump system that includes: a cooling assembly that is connected to a controller and includes a radiator, a water pump, and electric devices, each of which is connected through a cooling line; an air conditioning assembly connected by a refrigerant line and including an HVAC (Heating, Ventilation, and Air Conditioning) module that has a plurality of valves, an expansion valve, a compressor, an accumulator, an evaporator, an outside condenser, an inner condenser, a PTC heater, and an opening/closing door; and a heat exchanger that is connected to the cooling line and the refrigerant line, and is used to operate a heating mode, a cooling mode, and a humidifying mode according to a selection of a user, wherein during the heating mode, raising by the cooling assembly, the temperature of coolant that is supplied to the heat exchanger through waste heat that is generated from the electric devices and raising the temperature of refrigerant through heat exchange with the refrigerant that is supplied to the heat exchanger through the refrigerant line; passing by the air conditioning assembly the refrigerant that is heated by the heat exchanger through the accumulator and the compressor via the refrigerant line by opening a third valve to be supplied to an inner condenser of the HAVC module by an operation of a first valve; supplying the refrigerant passing the inner condenser to the heat exchanger by an operation of a second valve in an expanded condition through a first expansion valve; and opening the opening/closing door such that outside air passing the evaporator of the HAVC module passes the inner condenser, and inflow outside air passes the inner condenser to heat an interior room of the vehicle in conjunction with the operation of the operation of a PTC heater.
 7. The heat pump system control method of claim 6, wherein in the cooling mode, operating the water pump by the cooling assembly to supply coolant to the heat exchanger and to cool the electric devices in a condition that the radiator cools inflow coolant by an operation of a cooling fan, and cools refrigerant through heat exchange with low temperature coolant according to a predetermined condition; operating the third valve by the air conditioning assembly to supply the evaporator with expanded refrigerant such that the low temperature refrigerant that is cooled passing the outside condenser is supplied to the second expansion valve that is connected to the evaporator of the HAVC module, wherein the refrigerant that is evaporated through heat exchange with outside air in the evaporator passes the accumulator and the compressor to be compressed; operating the first valve to open the refrigerant line that is connected to the outside condenser such that a compressed refrigerant is supplied to the outside condenser; and closing the opening/closing door such that the outside air passes the evaporator to be cooled by the refrigerant supplied to the evaporator and is directly supplied to an interior room of a vehicle and that the cooled outside air is not supplied to the inner condenser.
 8. The heat pump system control method of claim 6, wherein in the dehumidification mode, cooling the coolant that is supplied to the radiator by the operation of the cooling fan of the cooling assembly, cooling the electric devices through the operation of the water pump, supplying the coolant to the heat exchanger, and cooling the refrigerant by exchanging heat with the coolant supplied to the heat exchanger; opening the third valve by the air conditioning assembly such that the coolant that is cooled while passing the heat exchanger is supplied to the second expansion valve that is connected to the evaporator of the HAVC, so as to supply the expanded refrigerant to the evaporator, wherein the refrigerant that is evaporated through heat exchange with outside air in the evaporator passes the accumulator and the compressor to be compressed; operating the first valve to open the refrigerant line that is connected to the inside condenser such that the compressed refrigerant is supplied to the inside condenser; operating the second valve to supply the refrigerant passing the inner condenser to the heat exchanger in an expanded condition through the first expansion valve, opening the opening/closing door such that outside air passing the evaporator of the HAVC module passes the inner condenser, and inflow outside air passes the inner condenser and the PTC heater to dehumidify an interior room of the vehicle.
 9. The heat pump system control method of claim 8, wherein in the dehumidification mode, the controller controls an opening rate of the first and second expansion valves to control an expansion rate of the refrigerant.
 10. The heat pump system control method of claim 6, wherein in the heating mode, cooling mode, and dehumidification mode, the controller controls operating power of the cooling fan and flowing rate of the water pump according to the temperature of the waste heat that is generated from the electric devices and the temperature of the coolant and the refrigerant.
 11. The heat pump system of claim 1, further comprising a four valve that is configured to make coolant to bypass the radiator according to a heating mode and a dehumification mode. 